102100021 has 4 divisors (see below), whose sum is σ = 102337344. Its totient is φ = 101862700.

The previous prime is 102100007. The next prime is 102100067. The reversal of 102100021 is 120001201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 102100021 - 2¹⁷ = 101968949 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102099977 and 102100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102100001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 118015 + ... + 118876.

It is an arithmetic number, because the mean of its divisors is an integer number (25584336).

Almost surely, 2^102100021 is an apocalyptic number.

It is an amenable number.

102100021 is a deficient number, since it is larger than the sum of its proper divisors (237323).

102100021 is an equidigital number, since it uses as much as digits as its factorization.

102100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 237322.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 102100021 is about 10104.4555024009. The cubic root of 102100021 is about 467.3855454892.

Adding to 102100021 its reverse (120001201), we get a palindrome (222101222).

The spelling of 102100021 in words is "one hundred two million, one hundred thousand, twenty-one".